Friday

April 18, 2014

April 18, 2014

Number of results: 445

**Diff eqn- IVP :)**

:)
*Saturday, March 12, 2011 at 7:03am by MathMate*

**Diff eqn- IVP**

oww...ok...
*Saturday, March 12, 2011 at 7:07am by shasha*

**Diff eqn- IVP**

thanzz again
*Saturday, March 12, 2011 at 7:03am by shasha*

**Diff eqn- IVP**

why stiffness (of a spring) ?
*Saturday, March 12, 2011 at 7:07am by shasha*

**Diff eqn- IVP**

This is an IVP (initial value problem). x"(t)=(6t-4) ms-2 ....(1) "...if the particle is at origin and has a velocity of ? when t=0." Integrate (1) with respect to t to find x'(t) and x(t). Do not forget the integration constants at each integration. Use the initial conditions...
*Saturday, March 12, 2011 at 7:03am by MathMate*

**Diff eqn- IVP**

A simple pendulum of length is oscillating through a small angle θ in a medium for which the resistance is proportional to the velocity. Obtain the differential equation of its motion and discuss the motion.
*Saturday, March 12, 2011 at 7:07am by shasha*

**Diff eqn- IVP**

It is an analogy. The general equation of motion make an analogy with a mass attached to the end of a spring: mx"+Bx'+kx=0 where k represents the restoring force per unit displacement.
*Saturday, March 12, 2011 at 7:07am by MathMate*

**Diff eqn- IVP**

A particle moves on the x-axis with an acceleration, a=(6t-4)ms⁻1. Find the position and velocity of the particle at t=3 , if the particle is at origin and has a velocity of when t=0
*Saturday, March 12, 2011 at 7:03am by shasha*

**Diff eqn- IVP**

The differential equation that governs the forced oscillation is shown below: 0.2 d²y/dt² + 1.2 dy/dt +2y = r(t) where r(t) is the external force. Given that r(t) = 5 cos 4t with y(0) = 0 . find the equation of motion of the forced oscillations
*Monday, March 14, 2011 at 7:36am by shasha*

**Linear Equations**

Y-X=4...(EQN 1) X-Y=3...(EQN 2) MAKING X THE SUBJECT IN EQN 2 X=3+Y SUBSTITUTING IN EQN 1 Y-(3+Y)=4 Y-3-Y=4 THE Y GETS ELIMINATED,HENCE THERE IS NO SOLUTION
*Tuesday, March 2, 2010 at 1:04pm by jessica*

**Chemistry**

I will refer to the three equations you have above as eqn 1, eqn 2 and eqn 3. Write equn 1 as is/ Reverse eqn 2. Eqn 3 as is Add the three equations together and you see that you get Mg(s) + 1/2 O2(g) ==> MgO(s) The delta H1 for eqn 1 is the delta H you measured. Delta H2 ...
*Tuesday, February 14, 2012 at 10:16am by DrBob222*

**Chem**

Reverse eqn A and add to 1/2 eqn B. Reversing an eqn changes sign of H. Taking 1/2 eqn changes H by 1/2.
*Tuesday, July 12, 2011 at 10:58pm by DrBob222*

**chemistry**

H2C2O4 + 2NaOH ==> Na2C2O4 + 2H2O eqn 1. moles H2C2O4 = grams/molar mass eqn 2. moles NaOH = 2 x moles H2C2O4 eqn 3. M NaOH = moles NaOH/L NaOH eqn 1 doesn't change. eqn 2 doesn't change. eqn 3 changes. If L NaOH is too high, then M NaOH is too low.
*Saturday, April 2, 2011 at 12:04pm by DrBob222*

**Math**

Let hockey pucks be a let honey sticks be b 1st eqn --> 5a + 3b = 23 2nd eqn --> 5a + b = 20 Eqn 1 - eqn 2 will give you 2b = 3 Hence b, which is one honey stick will cost 3/2 which is $1.50 Substituting b = 1.5 into eqn two will give u the answer the question is asking ...
*Tuesday, September 6, 2011 at 12:37pm by Anonymous*

**College Chemistry.**

Reverse eqn 1 and add to 3x eqn 2. That gives you the equation you want. Then for dH, change the sign of eqn 1 and add to 3x dH for eqn 2. By the way, you can't get what you want UNLESS you balance that equation you want. 2H2S + 3O2 ==> 2SO2 + 2H2O
*Tuesday, March 4, 2014 at 2:23pm by DrBob222*

**math**

If h=6, the IVP becomes dP/dt=P(7-P)-6, P(0)=Po Solve the IVP in implicit form though you should apply initial conditions. How small does Po have to be for the population to become extinct in finite time? explain using phase portrait.
*Sunday, October 16, 2011 at 6:07pm by mike*

**Chem Help!!!!**

I've thought about this for the last two hours and I don't think this is wrong. 0.771g Cr + 0.712g oxygen = 1.483g total. %Cr = (0.771/1.483)*100 = 51.99% %O = (0.712/1.483)*100 = 48.01% CrO, CrO2, Cr2O3, don't have these percentages. If the equation is 2Cr + O2 ==> 2CrO (...
*Monday, February 25, 2013 at 1:22pm by DrBob222*

**Chemistry**

Multiply eqn 1 by 2 and reverse. Multiply the delta H value by 2 and change the sign. Multiply eqn 2 by 2 and reverse it. Multiply the delta H value by 2 and change the sign. Add the new eqn 1 + eqn 2 along with eqn 3 and you get twice the equn you want. Add new delta H values...
*Wednesday, November 14, 2012 at 4:24pm by DrBob222*

**Chemistry**

Use eqn 1 as is. Call that Kp = Kp1 Use eqn 2, call it Kp2 Take 1/2 eqn 2 and K becomes sqrt Kp2. Then reverse the 1/2 eqn 2 which now becomes 1/sqrt Kp2. Tben add in eqn 1. Check to make sure you have the equation you want. Kp for the reaction you want we will call Kp3. Then ...
*Sunday, November 27, 2011 at 10:09pm by DrBob222*

**Chemistry**

I think you have some typos in your post but in general this is what you want. Easy to remember stuff. If eqn is doubled, K' is K^2. If eqn is halved, K' is square root K. If eqn is tripled, K' is K^3 etc. If eqn is reversed, K' = 1/K. If you want to show subscripts on Jishka...
*Saturday, May 28, 2011 at 2:34pm by DrBob222*

**Diff eqn- IVP**

Differential equations, initial value problem. The general equation of motion is: mx"+Bx'+kx=f(t), where the independent variable is t, and the displacement x is the dependent variable. In this case, external force f(t)=0, so mx"+Bx'+kx=0 substitute m=0.25, k=4, B=1 we have a ...
*Thursday, March 10, 2011 at 9:45pm by MathMate*

**diff eqn.**

You are not being asked to solve a differential equation. You only have to take the derivative of the y(t) function you are given. Just add the derivatives of the three separate terms. The derivative of -0.2451 cos(4t) is 0.9804 sin(4t) Your third term is illegible.
*Sunday, November 20, 2011 at 3:57am by drwls*

**elimination**

Multiply eqn 1 by 2 and eqn 2 by -3, then add the two equations to eliminate s. Then solve.
*Monday, October 14, 2013 at 3:51pm by DrBob222*

**MATH**

LAMONT IS REQ TO READ 1 BIO, 1 SCIENCE, AND 1 POETRY BOOK EACH MONTH. HIS BOOK CHOICES ARE: 2 DIFF BIOS 3 DIFF SCIENCE 3 DIFF POETRY HOW MANY COMBINATIONS OF REQ BOOKS ARE POSSIBLE?
*Monday, January 26, 2009 at 8:48pm by lANEY*

**algebra**

subtract equation 1 from eqn 2 (eqn3) 5 = 3 a + b subtract equation 1 from equation 3 (eqn4)13 = 8 a + 2 b now multiply equation 3 by 2 (eqn5) 10 = 6 a + 2 b subtract eqn 5 from eqn 4 3 = 2 a so a = 3/2 lo and behold now work your way back up to get b and c
*Saturday, November 22, 2008 at 5:00pm by Damon*

**Chem **

I assume you mean a drop (or several drops) from the buret that sticks to the side of the solution and isn't/aren't washed down. Let's look at how the calculations are done. eqn #1. moles NaOH = M x L = ? eqn #2. moles vinegar (acetic acid) = same as moles NaOH since the ...
*Thursday, June 23, 2011 at 1:09am by DrBob222*

**chemistry**

Use eqn 1 as is. Reverse eqn 2 and multiply by 2. (also multiply delta H by 2 and reverse the sign). Use eqn 3 as is. You should get 2Mg + 2O2 + 2H2 ==> 2Mg(OH)2 which is just twice what you want. So add the delta Hs from above and take half of it.
*Sunday, March 13, 2011 at 1:28pm by DrBob222*

**Intermediate Algebra**

m=2 and n=-7 I solved the second equation for n and got n=-4m+1 then plugged that into the first eqn for n and got m=2. finally i put m into the first eqn and got n=-7 to check, you can see the first eqn: m-2n=16 goes to 2-2(-7)=16 which is correct.
*Tuesday, February 22, 2011 at 12:09am by Alona*

**Chemistry**

eqn 1 CaF2 ==> Ca^2+ + 2F^- eqn 2 Ca^2+ + SO4^2- ==> CaSO4 ------------------------------- sum 1+2 CaF2 + SO4^2- ==> (F^-)^2 + CaSO4 since CaF2 and CaSO4 are solids we can cancel them since they are not involved in the Keq. You note that eqn 1 is Ksp for CaF2 and eqn ...
*Tuesday, April 8, 2014 at 11:59am by DrBob222*

**Chemistry**

eqn 1 as is eqn 2 reversed. eqn 3 reversed. Add 1+2+3 to find total equn which will give you twice the numbers for coefficients. Divide everything by 2. For dH, keep 1 as is, change the sign on 2 and 3 and add them, then divide by 2 to find dGo rxn Then dGo = -RTlnK you know ...
*Monday, November 5, 2012 at 11:50am by DrBob222*

**algebra 1,urgent**

the expression (4x^2-3x+1)-(x^3+2x+7) what is the coefficient of the x term in the simplified expression? what is an equation of a line parallel to the line with equation 2 y=14-6x a.y=-6x+18 b.y=-3x-9 c.y=6x+3 d.y=3x+8 Solve linear system, which substitution of unkowns is ...
*Tuesday, April 23, 2013 at 6:36pm by Sven*

**Ap Chemistry**

Two equations and two unknowns. Solve simultaneously. eqn 1. g NaCl + g KCl = 0.1586g eqn 2. mol AgCl from NaCl + mol AgCl from KCl = mol AgCl total Now put those into math form. Let X = g NaCl and Y = g KCl MM stands for molar mass. --------------------- eqn 1. X + Y = 0.1586...
*Sunday, February 2, 2014 at 4:59pm by DrBob222*

**Science**

Put slice of "potato" in four diff bowls. Add diff "solutions" to each bowl. Which is Dependent Variable and which is Independent Variable?
*Wednesday, October 26, 2011 at 11:46am by LW*

**diff eqn.**

y(t) = -0.2451 cos 4t + 0.9804 sin 4t + e^(-3t ) (A cos〖t+B〗 sin〖t)〗 y'(t) = ?
*Sunday, November 20, 2011 at 3:57am by Farah*

**Chemistry**

CH3OH(l) + 3/2 O2(g) CO2(g) + 2 H2O(l) ΔH°rxn = -726.4 kJ C(graphite) + O2(g) CO2(g) ΔH°rxn = -393.5 kJ H2(g) + 1/2 O2(g) H2O(l) ΔH°rxn = -285.8 kJ Reverse eqn 1, add in eqn 2, add in 2x the reverse of eqn 3. That will give you the final equation you want. When ...
*Sunday, September 18, 2011 at 4:59pm by DrBob222*

**differential**

dT/dt= k(T - Tm), t > 0 where k is a constant of proportionality, T and Tm are measured in degrees Fahrenheit, and time t is measured in hours. Because Diff wants to investigate the past using positive values of time, he decides to correspond t 0 with 6:00 A.M., and so...
*Thursday, September 27, 2012 at 4:23pm by armut*

**Chemistry**

Add eqn 1 as is to 3x eqn 2 to 2x the reverse of eqn 3. That will give you 2x the equn you want so take 1/2 of the final equation. When reversing an equation, change the sign of dH. When multiplying an equation, multiply dH by the same number. Add all of them take 1/2 final ...
*Wednesday, March 7, 2012 at 9:21pm by DrBob222*

**Chemistry**

First you find the Momentum (P) from the de Broglie eqn: P = h/lambda, where h is the Plancks constant. Then you find the velocity (v) from the eqn: P = m*v, where m is the Electron Mass. Then substitute v in the KE eqn: KE = 0.5*m*v^2. Add this KE to the Ionization Energy of ...
*Saturday, January 12, 2013 at 7:35am by Chemoengineer*

**Chemistry**

Your post flawed. The equation you want is not balanced. It should be 2NO2(g) ==> N2(g) + 2O2(g) Take eqn 1, multiply by 2 and reverse it. k' for the new equn is 1/k^2. Add eqn 2 as is with k2. The K for the desired reaction is Kc = k2*k'.
*Thursday, February 9, 2012 at 6:18pm by DrBob222*

**Diff eq**

y'(x)=sqrt2y(x)+7, y(4)=1 Solve the seperable diff eq
*Sunday, February 24, 2013 at 2:07pm by Melissa*

**Math**

I think you should plug in when x=1,2,3,4 into the eqn. then see if it increase or decrease when you finish X=1 Plug it into the eqn. y=5(1)+18 x=2 x=3 x=4 Get it?
*Tuesday, April 20, 2010 at 7:42pm by Skye*

**Chemistry**

Use eqn 1 as is. Take 1/2 of eqn 2 and reverse it. When reversing, the new k is 1/old k and when taking 1/2 we take the square root. Therefore, k for the reaction you want will be k2/sqrt k1. Then delta Go = -RTlnK.
*Thursday, September 22, 2011 at 2:10pm by DrBob222*

**trig**

the previous ans. is wrong as if we sq. the eqn. it generates false solutions a better method is to divide coefficients of sin and cos by root of sq. of coeff.ofsin+sq. of coeff of cos . that is main pt. remaining we will proceed by making it an argument in cos . and then make...
*Monday, December 5, 2011 at 5:27pm by piyush yadav*

**trig**

the previous ans. is wrong as if we sq. the eqn. it generates false solutions a better method is to divide coefficients of sin and cos by root of( sq. of coeff.ofsin+sq. of coeff of cos) . that is main pt. remaining we will proceed by making it an argument in cos . and then ...
*Monday, December 5, 2011 at 5:27pm by piyush yadav*

**chemistry**

Three equations and three unknowns but the way they are set up makes it as if it were two equations and two unknowns. Let X = mass NaX and Y = mass NaI and Z = mass NaNO3 (mm stands for molar mass) --------------------------- eqn 1 is Z + Y + Z = 0.8612g eqn 2 is mass AgBr ...
*Monday, April 7, 2014 at 8:15am by DrBob222*

**Chemistry**

For b, isn't delta Hf for elements in the free state zero? For a, I would do this. eqn1 H2 + F2 ==> 2HF -518.0 kJ(did you omit the minus sign)? eqn 2 2F ==> F2 -158.2 eqn 3 2H ==> H2 -431.8 Now add eqn 1 to 2 and 3 and you should end up with 2H + 2F ==> 2HF which ...
*Thursday, April 28, 2011 at 11:15am by DrBob222*

**Physics**

Use the eqn: v1'=v1*(m1-m2)/(m1+m2) M2=neutral car, its v2=0 since its at rest. m1=truck, v1=11.5. Then, once you have v1' you can sub it into m1v1+m2v2=m1v1'+m2v2' and find v2'. The first eqn is a special eqn only to be used when v2=0 and the collision is completely elastic. ...
*Saturday, November 19, 2011 at 11:30pm by Matt*

**physics**

Diffusion rate (moles/area*sec) = (Concentration gradient)*(Diff. coefficient) Shouldn't the concentration difference have units of mole/m^3 ? Or are you providing the value of (Diff. coefficient)/(thickness) ?
*Saturday, March 27, 2010 at 5:15am by drwls*

**chemistry**

You have two unknowns; therefore, you must have two equations in the two unknowns. Let X = mass K2CO3 and Y = mass Li2CO3 --------------------- eqn 1: X + Y = 0.500g eqn 2: (#Eq X) + (#Eq Y) = 0.0075 or (X/69) + (Y/37) = 0.0075 Solve eqn 1 and 2 simultaneously for X an Y. Then...
*Friday, February 22, 2013 at 11:57pm by DrBob222*

**Chemistry**

Two equations in two unknowns; solve simultaneously. Let X = mass NaCl and Y = mass K2SO4 ------------------- eqn 1 is X + Y = 10.0 eqn 2 is mass PbCl2 (from NaCl) + mass PbSO4(from K2SO4) = 21.75g. eqn 2 in terms of X and Y is this (X*MMPbCl2/2*MMNaCl) + (Y*MMPbSO4/MMK2SO4...
*Tuesday, March 18, 2014 at 10:21am by DrBob222*

**physics**

Sn=3.8+0.4-----(eqn 1) Sn=u+a(n-1/2) =u+an-a/2 Sn=(u-a/2)+an------(eqn 2) from 1 and 2 a=0.4m/s^2 u-a/2=3.8 u-0.4/2=3.8 u-0.2=3.8 u=6.0m/s
*Sunday, May 20, 2012 at 3:24am by choco*

**chemistry**

CH4 + 2O2 ==> CO2 + 2H2O C2H4 + 3O2 ==> 2CO2 + 2H2O Let x = mass CH4 and y = mass C2H4 ------------------ You need two equations. (eqn 1) is total mass = 5g (eqn 2) is (mass CO2+H2O from CH4) + (mass CO2+H2O from C2H4) = 14.5g ------------------------ Now convert those ...
*Thursday, July 25, 2013 at 12:54pm by DrBob222*

**Chemistry**

Multiply eqn 1 by 2. Add the reverse of eqn 2. This give you twice the equation you want so divide everything by 2. For dH. dH 1 + (-dH 2) = 2*dH total and divide by 2.
*Tuesday, January 22, 2013 at 6:40pm by DrBob222*

**chemistry**

M = mols/L mols = g/molar mass. eqn 1. M = mols/L (The definition of molarity is all you need to remember for this.) 0.10 M x 0.100 L = 0.010 mols eqn 2. mols = g/molar mass g = mols x molar mass g = 0.010 mols x molar mass NaCl = ?? You can put eqn 1 and 2 together to give ...
*Wednesday, January 16, 2008 at 2:33pm by DrBob222*

**Algebra 1**

1.To solve the linear system below, which substitution of unkowns is proper ? A.substitute 5x-16 for y in the first eqn B.substitute 5x+16 for y in the first eqn C.substitute 5x+12 for y in the first eqn D.substitute 7y-4 for x in the second eqn 2.A line with a slope of -2 ...
*Thursday, April 18, 2013 at 7:29pm by Ley*

**Algebra 1**

1. How many solutions does the linear system have ? 3x - y = 4 -3x + 11y = 2 2. A line passes through the points (6,4) and (5,-3). What is the equation of the line in point-slope form ? a. x - 6 = 7(y-4) b. y - 4 = 7(x-6) c. y + 6 = 7(x+4) d. y - 6 = 7(x-4) 3. A line passes ...
*Friday, April 19, 2013 at 10:33am by Shevani, help me*

**Physics**

How does the drag force on an object change if the object's area is halved while the wind speed is doubled, while keeping everything else the same? i think it would double if you use this eqn: f= 1/4 A v^2 can someone verify if this eqn is correct to use in this problem?
*Sunday, October 18, 2009 at 1:08am by Nancy*

**physical science**

if two lighting volts heat exactly they same place at they same time in are frame of ref.,it is possible that observed in other frames will see the volts heating at diff. time r at diff. places????? explain.
*Sunday, September 25, 2011 at 10:38am by angie*

**algebra**

Eqn (1) to be mly by 4, then we have 4x-4y=-4, (2)5x+4y=-23 ---------- 9x+ 0=-27 9x=-27 x=-27/9=-3 x=-3. to get y, we substitute in the eqn(1) (x-y=-1) as -3-y=-1 -3+1=y y=-2. Therefore, we get x=-3 y=-2
*Monday, October 20, 2008 at 11:55pm by Rico_TLP*

**Chemistry**

Add eqn 1 to eqn 2 to obtain A+2B ==> 2C 2C ==> D ------------ A + 2B ==> D so K' = k1*k2. You want the reverse of this rxn; therefore, you want 1/K'.
*Friday, February 21, 2014 at 1:18pm by DrBob222*

**math**

I worked the problem like this. not sure if i am using male or female as the base. abs diff= 1350-1010=340 relative diff= 1350-1010, divided by 1010=.336633663 or 33.7%. did i do it the way they problem asks or did i do it backwards? thanks
*Tuesday, March 30, 2010 at 9:06pm by Amy*

**Maths**

In an orthonormal system, you're given the following: Point P(1,2) Lina a=cartesian eqn:4x-3y+6=0 Line b=parametric eqns:x=-5+3& y=-& (real n°) Circle z=cartesian eqn:x²+y²-2x-3=0 (a)Calculate the angle between lines a an b (b)Calculate the coordinates of the point of ...
*Sunday, May 4, 2008 at 4:14pm by Anonymous*

**Mathematics**

In an orthonormal system, you're given the following: Point P(1,2) Lina a=cartesian eqn:4x-3y+6=0 Line b=parametric eqns:x=-5+3& y=-& (real n°) Circle z=cartesian eqn:x²+y²-2x-3=0 (a)Calculate the angle between lines a an b (b)Calculate the coordinates of the point of ...
*Sunday, May 18, 2008 at 9:14am by Anonymous*

**chemistry**

I did this in my head and I BELIEVE (but you need to try it to see) eqn 3 reversed. Add to 2x eqn 1 and add to the reverse of 2 x equn 2. Add the dH values. When you multiply a rxn by a coefficient do the same for dH. When you reverse and equation change the sign on dH.
*Wednesday, March 5, 2014 at 6:15pm by DrBob222*

**Math**

LOL I can't figure this out. It should be easy it's been years since I've been in school and my son has no idea. The product of two numbers is 63. Their sum is 16. What are the numbers? Thanks for the help! Let's factor 63. 1 x 63; 3 x 21; 7 x 9. Which of those pairs of ...
*Wednesday, January 17, 2007 at 4:46pm by Lisa*

**math**

child's fair ticket is $5 and adult fair ticket are $5. 1050 people attend the fair. fair collects $7350. how many of each type of ticket were sold? sorry. child is $5 and adult is $8 Try this: x = no. of children attending the fair y = no. of adults attending the fair so, 5x...
*Friday, February 2, 2007 at 1:14am by gaynell*

**Chemistry**

Balance the eqn Na2CO3 + 2HCl -> 2NaCl +H20 + CO2 From the balanced eqn you can see that one mole of CO2 is produced. Then at stp 1 mole of gas takes up 24 litres (I think, check this on google) therefore v= 24 litres. :)
*Sunday, October 3, 2010 at 5:02pm by Rose*

**chemistry**

AgBr==> Ag^+ + Br^- Ag^+ + 2NH3 ==> Ag(NH3^+ eqn 1..Ksp = (Ag^+)(Br^-) Kf = [Ag(NH3)2^+]/(Ag^+)(NH3)^2 Let S = solubility, then eqn 2..S = (Br^-) = (Ag^+) + [Ag(NH3)2^+] eqn 3..3.9 = (NH3) + (NH4^+) + 2[Ag(MH3)2^+] Three equations as above. 1..as is 2..(Ag^+)<< [Ag...
*Friday, November 4, 2011 at 1:51am by DrBob222*

**Chemistry **

I would do this. x+y = 9.0 0.50x + 0.20y = 3.90 ------------------Multiply eqn 1 by -(1/2). -0.50x - 0.50y = -4.50. keep eqn 2 as is. 0.50x + 0.20y = 3.90 -----------------------Now add the two. You see the x term cancels. Solve for y, then substitute y back into one of the ...
*Saturday, July 9, 2011 at 6:15pm by DrBob222*

**Chemistry**

P4(s) + 10 Cl2(g)--> 4 PCl5(s) ΔH°rxn= -1774.0 kJ PCl3(l) + Cl2(g)--> PCl5(s) ΔH°rxn = -123.8 kJ Use eqn 1 as is. Multiply eqn 2 by 4 (multiply delta H rxn by 4 also), reverse it (change the sign of delta H x 4), and add to eqn 1. That will give you the ...
*Sunday, May 1, 2011 at 10:53pm by DrBob222*

**chemistry**

This is an application of Hess' Law. You want to arrange the three equations given to obtain the desired equation. Reverse eqn 3 and 2 and add i eqn 1. When you reverse an equation, change the sign of delta H. If you follow my directions, see if you get the equation you want ...
*Monday, January 23, 2012 at 8:05pm by DrBob222*

**algebra**

how would i find an equation of a line that goes through points(1,6) and (3,10)?? thanks A straight line is y=mx+b Substitute the points to make two equations. 6=m(1)+b 10=m(3)+b Two equations; two unknowns, m and b. Solve for m and b, then plug back into y = mx + b. That will...
*Friday, December 22, 2006 at 9:49pm by jasmine*

**Math**

solve the ivp dy/dx = 1/(sqrt(1-x^2)) with initial condition y(sqrt(3)/2)=0
*Wednesday, September 19, 2012 at 12:33am by Mark*

**math Steve for your help**

2KNO3 ==> 2KNO2 + O2 and 2NaNO3 ==> 2NaNO2 + O2 Let X = mass KNO3 and Y = mass NaNO3 --------------------- eqn 1 is X + Y = 3.2 eqn 2 is X(molar mass KNO2/KNO3) + Y(molar mass NaNO2/NaNO3) = 2.64 Solve the two equations simultaneously to find X, then %X = (mass X/3.2)*...
*Sunday, December 29, 2013 at 2:13pm by DrBob222*

**math**

a childs bank contains $6.30 in dimes and quarters. there are twice as many dimes as quarters. how many of each kind of coin are in the bank? let d = #dimes and q=#quarters. The total is worth $6.30. eqn 1 is 0.10*d + 0.25*q=$6.30 eqn 2 is 2*#quarters = #dimes or 2q=d. Two ...
*Wednesday, November 29, 2006 at 2:53pm by katie*

**chemistry**

Your post is garbled. I think you means this 2BaO + O2 ==> 2BaO Ba + CO2 + 1/2 O2 ==> BaCO3 ============================ Take 1/2 equation 2 and add to the reverse of equation 2 and see if that isn't the equation you want. For delta H, take 1/2 DH(eqn 1) and add to the ...
*Monday, October 25, 2010 at 5:52pm by DrBob222*

**CHEMISTRY PLEASE HELP**

a)Here are the equations used for the standardization of NaoH> 1. moles KHP = grams/molar mass 2. moles NaOH = moles KHP 3. M NaOH = moles NaOH/L NaOH If KHP is spilled that means grams is too small in equn 1 which makes moles small; eqn 2 makes moles NaOH too small, #3 ...
*Monday, October 24, 2011 at 8:03pm by DrBob222*

**chemistry**

1. NH3 + H2O ==> NH4^+ + OH^- 2. Zn + 2OH^- ==> Zn(OH)2 3. Zn(OH)2 + NH3 ==> Zn(NH3)4^+2 + 2OH^- 4. Ksp = (Zn^+)(OH^-)^2 5. NH4Cl ==> NH4^+ + Cl^- NH3 produces OH^- (eqn 1) which combines with Zn (eqn 2) to form Zn(OH)2, a white ppt. An excess of NH3 gives eqn 3 in...
*Saturday, April 2, 2011 at 11:54pm by DrBob222*

**Differential Equations**

scroll down through this: http://hyperphysics.phy-astr.gsu.edu/hbase/diff.html
*Thursday, January 31, 2013 at 11:46am by Damon*

**Differential Equations**

scroll down through this: http://hyperphysics.phy-astr.gsu.edu/hbase/diff.html
*Thursday, January 31, 2013 at 3:41pm by Damon*

**Math**

The numbers 4; 6; 13; 27; 50; 84 do not form an arithmetic progression as the differences between succsessive terms are not constant. If you take the successive differences of the terms given, n.......1....2....3....4....5....6... N.......4....6...13...27...50...84... 1st Diff...
*Friday, May 11, 2012 at 6:47am by tchrwill*

**algebra 2**

Let section B has x seat , section C has y seat. section A has (x+y)seat (x+y)+x+y =49000 x+y = 24500 equation1 25(x+y)+20x +15y = 1052000 equation2 9x+8y= 210400 equation2 solving eqn.1 & eqn. 2 by substitution method you will get x=14400 y=10100 section A =24500 section B =...
*Thursday, September 4, 2008 at 12:07am by William*

**chemistry**

If heat of reaction, Ca(s) + 2H+(aq) Ca2+(aq) + H2(g) , is - 544 kJ/mol, heat of reaction, CaO(s) + 2H+(aq) Ca2+(aq) + H2O(l) , is -192 kJ/mol. and heat of formation of water is -286, what is heat of CaO? i found that the formation of CaO is -638. However, I'm confused about ...
*Sunday, February 11, 2007 at 1:15am by nicholas*

**maths**

1. Identify two examples of exponential r/s 2. The data below shows how the the population of the world has changed over the last three hundred years Year population(mill) 1650 500 1700 600 1750 700 1800 900 1850 1300 1900 1700 1950 2500 2000 7000 The data can be modelled by a...
*Monday, February 26, 2007 at 8:41am by me again Thanks sooo much*

**math**

5[12x+16y=1/5] 60x+80y=1--->eqn 1 4[13x+24y=1/4] 52x+96y=1 36[60x+80y=1] 30[52x+96y=1] 5[12x+16y=1/5] 60x+80y=1--->eqn 1 4[13x+24y=1/4] 52x+96y=1--->eqn 2 [60x+80y=1]36 [52x+96y=1]30 2160x+2880y=36 -1560x+2880y=30 600x=6 x=1/100 substitute the value of x in any ...
*Sunday, April 7, 2013 at 4:24am by jessica*

**physics emergerncyy!**

use the eqn v2'=v1(2*m1/(m1+m2)) This eqn is specially derived fro elastic collisions where v2=0. The speeds should be components; north, south, east, west or up, down, leftm, right etc. Anyways, find the components and then use pythagorean theroem. (once you have v1, you can ...
*Saturday, November 19, 2011 at 11:23pm by Matt*

**Science ENGR Part 2**

How many electrons are in the upper level? Problem 2 Problem 1 of chapter 6 of the course-pack. Use eqn. 2.27 for the definition of decibel. Eqn. 2.27 : A(w)=-20log|T(jw)| db Use the plot to calculate the repeater distance in a long haul optical communication system. Assume ...
*Sunday, November 19, 2006 at 5:45pm by Pam*

**Calculus**

Solve the IVP {y'=-(sinx)y + xexp(cosx) y(0) = 1 Please show me step by step. Do I need to find out if this is exact? Do I use an integrating factor?
*Wednesday, October 7, 2009 at 12:43am by Ella*

**chemistry**

First you solve for I (vant hoff factor) in the freezing point eqn. You are provided molality, delta fp and can get the kf from a textbook (hint since its aqueous, use value for h2o). Next, take this I value and plug it into the boiling point eqn with the given molality and ...
*Tuesday, December 5, 2006 at 2:59pm by erin*

**chemistry**

First you solve for I (vant hoff factor) in the freezing point eqn. You are provided molality, delta fp and can get the kf from a textbook (hint since its aqueous, use value for h2o). Next, take this I value and plug it into the boiling point eqn with the given molality and ...
*Tuesday, December 5, 2006 at 2:59pm by erin*

**Chemistry - Quantitative analysis**

The combustion equations are as follows: C6H12 + 9O2 ==> 6CO2 + 6H2O 2C2H4O + 5O2 ==> 4CO2 + 4H2O This is an equation with two unknowns. Here are the two equations which you should solve simultaneously. Let Y = milligrams cyclohexane and Z = milligrams oxirane...
*Monday, January 16, 2012 at 2:57pm by DrBob222*

**Diff eqn**

This is not an initial value problem! External forces are zero, so the governing equation is homogeneous: mx"+Bx'+kx=0 x"=d²x/dt². x'=dx/dt x=displacement, positive to the right m=mass B=resistance proportional to the velocity k=stiffness (of a spring), which is ...
*Saturday, March 12, 2011 at 7:07am by MathMate*

**Chemistry**

I've just moved and don't know where my tables are but here is what you do. MO2 ==> M + O2 dG = 290.5 kJ/mol C + O2 ==> CO2 dG = look in the tables for dGf. Add equation 1 to equation 2 to obtain the equation you want which is MO2 + C ==> M + CO2 and dGrxn = dGf for ...
*Tuesday, January 14, 2014 at 10:25pm by DrBob222*

**Chemistry**

Au has changed from +3 in AuCl4^- top zero in Au. Sn has changed from +2 to +4. I think the easy way is this. Au^3+ + 3e ==> Au Sn^2+ ==> Sn^4+ + 2e ---------------------- Multiply eqn 1 by 2 and eqn 2 by 3 and add. 2Au^3+ + 3Sn^2+ ==> 2Au + 3Sn^4+ Then add 8Cl^- to ...
*Thursday, June 14, 2012 at 9:37pm by DrBob222*

**Algebra 1 HELP PLZ!!!**

Use the Substitution method to solve the system of equations. x + y = -4 x - y = 2 PLz HELP!! I'M NOT BOB BUT I CAN HELP ITS REALLY SIMPLE ALGEBRA X + Y = -4......EQN 1 X - Y = 2.....EQN 2 From EQN 2, let x = 2 + y Substitute that into EQN 1 x - y = -4 (2+y) + y= -4 2 + 2y= -4...
*Thursday, November 2, 2006 at 7:03pm by Margie*

**Calculus**

A cylindrical drum is made to hold exactly 1m^3 in its interior. Assume that the material for the top and the bottom costs $20 per m^2, while that for the side costs $10 per m^2. Determine the radius of the drum that minimizes the cost of the material used. ____ / \ |\____/| &...
*Sunday, December 10, 2006 at 10:18am by Frederique*

**chemistry**

The idea of predicting which is ionic, which covalent, which polar covalent depends upon some man made definitions and how to interpret them. Look up the value for the electronegativity (EN) for each element. If the difference is about 1.9 or so it is about 50% covalent/50% ...
*Sunday, February 9, 2014 at 8:17pm by DrBob222*

**PHYS101**

A2 = A1/4, so you know A1v1 = A2v2 A1v1 = A1/4v2, cancel out the A1's v1 = 1/4 v2 v2^2 = 16v1^2 --- eqn 1 change in pressure = (rho)gh = 3332 N/m^2 3332 = 1/2(rho)(v2^2 - v1^2) 3332 = (1/2)(1000)(v2^2 - v1^2) v2^2 = 6.664 + v1^2 --- eqn 2 16v1^2 = 6.664 + v1^2 v1 = 0.6665 m/s...
*Monday, April 19, 2010 at 6:39am by Anonymous*

**math**

two equations two unknowns: 3r - 2s = 0 2r + 3s = 13 3r - 2s = 0 =>r=2s/3 Substituting in (eqn 2)=> 2*2s/3 +3s = 13 solve for s =>s((4/3)+3)=13=>s(13/3)=13=>s=3=>using eqn 1 r=2
*Monday, June 8, 2009 at 11:07pm by DAS*

**chemistry**

I gave you the answer for a from your first post. For #2. (1) delta T = Kf*m (2) molality = moles solute/kg (3) molar mass = grams solute/# moles. So if some of the solvent is spilled before the solute is added, that will mean the molality is too large (equation 2). So when we...
*Wednesday, February 24, 2010 at 12:16am by DrBob222*

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